Enzyme applications, factors influencing

In the development and application of biosensors based on enzymes several factors required for the catalytic process have to be taken into account, which are either directly involved in catalysis or influence the formation of the enzyme-substrate complex. They are designated coenzymes, prosthetic groups, and effectors. 

Plant Proteases. These include the well known proteases papain, bromelain and ficin. Most plant enzymes are available as comparatively unpurified powder extracts, although papain is notable for being available in a stabilized and purified liquid form. Prospects for increased supply of plant enzymes, in response to greater use in traditional applications or for new processes, depend on several factors. Tlie influence of cultivation conditions, growth cycle and climate requirements make new supplies long term projects. 

The following factors appear to control the emulsification properties of milk proteins in food product applications 1) the physico-chemical state of the proteins as influenced by pH, Ca and other polyvalent ions, denaturation, aggregation, enzyme modification, and conditions used to produce the emulsion 2) composition and processing conditions with respect to lipid-protein ratio, chemical emulsifiers, physical state of the fat phase, ionic activities, pH, and viscosity of the dispersion phase surrounding the fat globules and 3) the sequence and process for incorporating the respective components of the emulsion and for forming the emulsion. 

Enzyme immobilisation on mesoporous silica has also proved attractive for biocatalysis applications, particularly in nonaqueous solvents, since immobilisation of enzymes results in increased mechanical stability and potential for catalyst recyclingMany factors, such as relative size of nanopore/enzyme, nanopore volume, surface characteristics of support/enzyme influence enzyme loading and activity Enzymes... 

In the past decade or so, lipase-catalyzed esterifications and transesterifications in anhydrous media (e.g., organic solvents and supercritical fluids) have been an area of intensive research. In particular, the use of organic solvents, which normally allow a higher stability of enzymes than in water (Bock, Jimoh, Wozny, 1997), has been demonstrated. Reviews of the applications have been made by Hail Krishna and Karanth (2002) and Gandhi et al. (2000), dealing with fundamental and practical aspects of lipase catalysis. In particular, they concentrated on various immobilization strategies and factors (e.g., temperature, reaction medium, water activity) as weU as the methods of preparation (which affect and influence the stability of the lipases). 

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